Constitutio Romana

The Constitutio Romana was an agreement between Pope Eugene II and King Lothaire of Italy formed on 11 November 824 AD that stated that no pope could be consecrated until his election was confirmed by the Frankish emperor. In 884 AD, Pope Marinus I revoked the agreement after years of Frankish dominance over the papacy.

History
Pope Eugene II was consecrated as pope in 824 AD following the death of Pope Paschal I, with the nobility electing him because of their wishes to have their Frankish allies control the papacy instead of the Roman clergy. Eugene immediately faced opposition from Antipope Zinzinnus, who was elected by the plebeians, so he called on the Franks to assist him. Lothaire of Italy, the son of the Frankish emperor Louis the Pious, provided stability in Italy, but he also took the time to work the Papal laws around so that they would favor the Franks. Lothaire declared that the pope would be elected by nobles, and that no pope would be consecrated until the emperor confirmed him. This gave the Frankish emperors of the Holy Roman Empire authority over the papacy, and would allow them to replace the Roman or Byzantine Empires as the leaders of Christianity.

The Constitutio Romana was followed by two of the successors of Eugene, but in 844 AD Pope Sergius II was consecrated unanimously by the nobles and bishops without the go-ahead from Louis the Pious. He was neither consecrated in the presence of Frankish envoys nor swore an oath of homage to the Emperor, and the new Holy Roman emperor Lothaire sent his son Louis II of Italy to enforce Frankish hegemony over the Papacy. In an accomodation to the Franks, Sergius crowned Louis king of Lombardy. The papacy was forced to abide by the law until 884, when Pope Marinus I issued a decree stating that emperors would not intervene in person or through ambassadors in electing a pope. This ended Frankish dominance over the papacy.